With improved performance and price-reduction of computers, the construction of a network system has been recently developed where peripheral equipments shared in a communications network such as LAN (Local Area Network) performs various operations under the instructions from computers.
Peripheral devices shared in the communications network are, for example, a copier, a scanner, an image forming device such as MFP. Such a network system is constructed that a plurality of image forming devices are connected to each other over the LAN. This allows the plurality of image forming devices to execute print jobs transmitted from a computer. In such an image output system, a device to perform output in response to each print job supplied is usually designated at the time when an output instruction is issued, and the print job is transmitted to the designated device.
In such an image output system, however, it can be considered that there could occur concentration of job output requests to a specific image forming device. Specifically, there could occur the following situation: one device is in a standby state, while the other one is so busy that it waits for outputs for incoming jobs. This may cause inefficient use of the image forming devices.
On this account, it is preferable that an image forming device to execute a print job is selected according to the printing status of the image forming devices. Further, it is preferable that if the amount of data to be processed for a print job is large, the load of processing the data can be shared by a plurality of image forming devices.
Further, the case of using MFPs for the image forming devices causes the following situation: Under circumstances where all of the MFPs connected to the communications network are in the course of printing, a user who needs copying must wait until any of the MFPs completes its printing operation. It is therefore preferable that the distribution of jobs is controlled so that there always exists an image forming device which is not busy.
In order to solve such a problem, an image output system has been suggested that the settlement (negotiation) of jobs is performed among the plurality of image forming devices on the communications network, and such settlement can be realized with an increased use efficiency of the image forming devices and without increase of the load on the network (see, for example, Japanese Unexamined Patent Publication No. 319533/1997 (Tokukaihei 9-319533; published on Dec. 12, 1997), Japanese Unexamined Patent Publication No. 003259/2000 (Tokukai 2000-003259; published on Jan. 7, 2000), Japanese Unexamined Patent Publication No. 066950/2001 (Tokukai 2001-066950; published on Mar. 16, 2001), Japanese Unexamined Patent Publication No. 331453/1999 (Tokukaihei 11-331453; published on Nov. 30, 1999)).
For example, Japanese Unexamined Patent Publication No. 319533/1997 (Tokukaihei 9-319533) discloses an image output system such that printers having common characteristics are grouped together so that output data is distributed automatically to a printer having the capability that the user needs. In this image output system, a printer server manages the printers having the same capability by grouping such printers.
A host that provides an instruction for a print job designates a printer group supporting the capability that is needed for printing operation of the instructed print job, rather than designates a specific printer to execute the print job. Considering operating statuses of the printers which are included in the printer group having been designated by the host, the printer server selects a printer to execute the print job, and transmits print data to the selected printer so that the selected printer executes the print job.
However, the conventional image output system described above has the following problems: In the image output system disclosed in Patent Document 1, the printer server performs a centralized management of all the printers on the communications network. In this arrangement, there is the problem that inoperable condition of the printer server for some reason stops the operations of the overall image output system.
Further, receiving a print job from the host, the printer server temporarily holds data of the print job. Then, the printer server selects a printer to execute the received print job from the printer group supporting the capability that is needed for printing operation of the received print job, considering their operating statuses. Thereafter, the printer server transmits the temporarily held print job to the selected printer. That is, the print job having been transmitted from the host is temporarily held by the printer server. After having completed distribution process, the printer server transmits the print job to the selected printer. This raises the problem of a long processing time between the instant when the print instruction is given and the instant when the printing operation is started. This problem becomes more pronounced especially in the case when a plurality of print jobs are transmitted to the printer server around the same time.
Further, the print job is transmitted to only the printer that has been selected by the printer server. Thus, under the circumstances where the selected printer cannot perform printing operation when trouble occurs, the printer server must be capable of transferring to another printer the print job that the selected printer has been supposed to execute. In such a case, when the printer server detects that trouble occurs in one printer, the printer server performs the process of selecting other printer to execute the printer job having been previously instructed to the printer with the trouble, and thereafter performs the process of transmitting the print job to newly selected printer. This raises not only the problem that the load on the printer server increases in processing, but also the problem that a quick response to the print job cannot be performed due to much time required for the transfer of the print job.
The present invention has been attained in view of the above problem, and an object thereof is to provide a line concentrator, a relay control method, a relay control program, a storage medium storing the relay control program, an information processing device, a DHCP server, a DHCP processing method, a DHCP processing program, a storage medium storing the DHCP processing program, and an information processing system, all of which solves the problems, such as concentration of jobs to a specific information processing device, and realizes a rapid data transfer processing.